Help me understand - plz

[CaptainAL]

The bonus is added to the total ship speed, hence a ship with six Quantum I Engines (Propulsion 10) gets an additional 3 movement points - the ship can move at speed nine. A baseship with two quantum engines moves at speed five (2 + 3 bonus points). With solar sails III a ship with six quantum engines will move 12 (6 base points +3 quantum bonus +3 solar sail bonus). The fastest any ship can go is 12 UNLESS the owner is a propulsion expert, then it is 13. There also is the emergency propulsion component that can add up to five movement points when used. So it is possible for a ship to move 17 sectors (or 18 for propulsion expert) in one turn if emergency propulsion is used.

One point about combat speed is that it is 1/2 that of normal travel speed. The combat speed increases on the odd number movement point, i.e. a ships with both speeds 9 and 10 move 5 in combat; likewise, ships with speeds 11 and 12 move 6 in combat. If combat speed is the only consideration for an engine upgrade, then it would not make sense to upgrade a ship with speed 9 to a ship with speed 10 since the combat speed would remain unchanged at 5 for both classes.